IL 31 follows the Fox River along the western bank. It parallels IL 25, which travels along the eastern bank of the Fox River. It travels concurrent with IL 120 in McHenry.
The Western Algonquin Bypass was completed in 2014[3] and redirects traffic around downtown Algonquin.
History
SBI Route 31 traveled from Quincy to Canton along various routes.[4] This was dropped in 1935 and was replaced with US 24.[5] In 1937, it was reapplied along other routes on its modern routing. There have been no changes to the routing since.[2]
U.S. Route 430 (US 430) was commissioned from 1926 to 1935 in the U.S. state of Illinois, and traveled from Aurora to Crystal Lake.[6] It traveled concurrently with US 30 from Aurora to Geneva at present-day IL 38. In 1934, US 430 was removed north of West Dundee after US 14 was formed.[4] In 1935, US 430 was decommissioned after US 330 was extended north from Geneva to West Dundee.[5] The northern extension was later removed in 1937 in favor of IL 31 and the western extension of US 330 to Dixon.[2][7]
Future
McHenry
The intersection of IL 31 and IL 120 is now the most congested intersection in McHenry County.[citation needed]
IDOT is currently in Phase 1 of a planned widening of IL 31 from IL 176 in Crystal Lake to IL 120 in McHenry.[8]
A bypass of McHenry continues to appear in documents planning for a Metra station at Prairie Grove, that include an interchange with the existing IL 31 alignment and the proposed west McHenry bypass alignment to the north of Gracy Road.[9]
The west McHenry bypass was originally planned to travel over undeveloped farm lands from north of IL 31 and Gracy Road to IL 120 and Ringwood Road. The corridor was planned to be protected from development in the mid-1990s, but because of a lack of funding, the corridor was never protected from development[10] and has since been developed.[11]
^ abIllinois Secretary of State; Rand McNally (1934). Official Road Map Illinois (Map). [c. 1:950,000 and c. 1:1,110,000]. Springfield: Illinois Secretary of State. OCLC183709045 – via Illinois Digital Archives.
^ abcIllinois Secretary of State; H.M. Gousha (1935). Official Road Map Illinois (Map). [c. 1:950,000 and c. 1:1,110,000]. Springfield: Illinois Secretary of State – via Illinois Digital Archives.
^Illinois Secretary of State (1932). Official Illinois Highway Map (Map). [c. 1:950,000 and c. 1:1,110,000]. Springfield: Illinois Division of Highways – via Illinois Digital Archives.
^Illinois Secretary of State; Rand McNally (1939). Illinois Road Map (Map) (1939–1940 ed.). c. 1:918,720. Springfield: Illinois Secretary of State – via Illinois Digital Archives.